R programming class week 4
Some skills about debugging.
The Sys.time() for get time and profiler that can help find out the time distribution for programs.
Working on the assignment 3 . and there are several useful method learned.
subset: get subset from a vector
min: min value for a vector
which: used in dataframe to get a logical vector, with expression.
try to start the the Visual Studio Code. that seems promising.
Misc,
the fried
Learned several split-and-combine functions
lapply : return a list;
sapply : simplified result of lapply
apply: apply functions on the matrix, directions (rows or columns) could be chosen.
tapply: subsetting the vectors and then apply functions on each sub group and get result.
mapply : apply funcitons on multiple inputs.
split: split a matrix according to subsetting index. combine with lapply or sapply it could achieve effects as tapply(but potentially more powerful)
Tried butterknife
finished the interface pattern
And read the composite design pattern.
The composite pattern suits for tree structure.
There are three classes:
Component : the base class for composite and leaf
Composite: a concrete component class that ‘contains’ multiple component classes which could be either composite or leaf.
leaf: just a concrete component class
There are also two ways implementing it:
transparent: all methods are in base class – Component
safe : some methods are in composite class, avoid accessed through leaf.
some practice of numberpicker, I could not find a way to programmatically change the font size of numberpicker. There is a way to do it fixed, that is create a custom numberpicker and assign the text size to the EditText. I have to say the “iterating children view” method is the first time come across me and I was really like “Ah! We could do that ?!”
Forget an access token for my instagram tutorial.
THat is the reason why the “grams” variable in index page keeps producing error “forEach() function on undefine” .
Practice the basic R concepts with Swirl().
Things goes fine, I just start wondering what the exact type language is R.
The R control syntax,
if… else…
while…
for loop and several usage of for loop
repeat, next, break
Some practice in ‘themes’ and ‘styles’.
design pattern- adapter.
Adapter is built to allow two different interfaces could communicate with each other without changing the interfaces.
R programming :
Function :
Scoping:
Misc
Introduced Gordon, because T is leaving.
start the R programming of the Data scientist’s tool box.
About changing the font for entire application,
There are some promising ways.
A stackoverflow answer introduced a method implemented by reflection.
Calligrahpy is a library that could be imported from gradle directly.
End the design pattern about the factory.
Start the abstract factory. It seems that abstract factory is for factory with complex products.
Data scientist toolbox Week3.
Basically just introduced the principles of experiment. And also some important terminologies.
Change fonts of android turns out to be a tricky task.
Calligraphy turns out to be a workable library but it does not work with our one.
Some other tricks does not apply also. I need to investigate what is the reason for that.
Java Reflection is an interesting function. Maybe it is time to read the thinking in java.
Beside the simple factory pattern. there is also factory pattern
The simple factory pattern is constrained as that addition of new product need to modify the factory class.
So, an abstract factory class could be introduced and every new product would has its corresponding factory sub-class.
Some follow up of the data scientist tool box.
Reviewed some git and markdown
Spend some time on TST.
And installed ToDoList, StarUML. Such things seems being able to improve my efficiency.
I start feeling my old code is not abstract enough.
Simple factory pattern:
A factory class that receive a concrete product class identifier and return an object of that specific product sub-class.
Start the data scientist tool box.
Just the overview starters. Not something very useful. take it as English practice.
After reads some Design patterns, I really feels that there are a lot of flaws in my code and I really should improve the codes.
Single Responsibility principle,
a class should only work for only thing
open-closed principle.
Open for expanding, close for modification.
Liskov substitution principle (LSP).
All base class should be able to be replaced by its a sub-class.
Watched first several videos from basic statistics of Coursera.
They introduced more variable types to me. Previously I only know there are “nominal” and “ordinal”. And they introduced “interval” and “ratio” which belongs to a “quantitative” category. other than that there is not some thing new.
Android:
<Activity> in the Manifest defines the information related with a specific activity.
<meta-data> defines several meta- information about a specific attributes which could belongs to “Activity”.
How does startActivityforResult() get the result back in onActivityResult()?
Using setResult(Intent intent). where the intent could contain a bundle which contains the complex information.
Builder type. is about building complex objects.
There are “Product” class defines what variables should product have.
abstract “Builder” class defines what a concret builder should have.
concret “builder” class that could be used directly to populate several variables in “Product”
And there could be a “Controller” controls the flow of building by calling the methods belongs to “Builder” class.
Reviewed the linear algebra part of deep learning.
Looked at the android-wizard library and created two new custom “pages” – number picker page and time picker page.
Continues with the Design pattern
The decorator pattern is about adding new functions to specific component without introducing new complexities.
The basic idea is :
An decorator will get an original component as its initializer and then add more functions under the name of some “super method”.
Then this decorator is still being a “component” so that everything is “just like original and transparent.”
Or this decorator could be a “concrete decorator” which will allow client side use the “new add functions” specifically with the cost of “simplicity”.
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